Super Time Force

This'll be somewhat tough to explain, but alas I'll try.

I'm going to use the first level of 198X for reference, being the first level you'll play I imagine it's the easiest way to achieve this. That being said, this can be achieved on any of the levels where shards can be collected.

So, to unlock this you need to first identify the Looker, which is the floating collection of squares that appears by the exit of every level. Once you collect it, a small timer appears in the upper right corner of the screen. After grabbing it, you'll need to rewind all the way back to the beginning of the level.

This timer will now read 20.00 seconds.

You now have just 20 seconds to get from start to finish. The catch is that you must collect the level's three collectible shards along the way.

If you reach the Looker again—who, upon second visit, takes another form—before the timer expires, you'll be treated to a cutscene and an achievement.

It's as simple as that.

As far as tips go for the level itself—again, I'm using the first level in 198X as my personal example—I'd recommend beginning with Zackasaurus, as this'll allow you to jump from the tank's main gun and execute a chain of head bounces. This gets you off to an ideal start, leading to the first shard.

As far as timing goes, I had about 9.5 seconds left when I hit the door where you meet Jef Leppard.

I then had just 4.5 seconds left when I hit the second shard, which mightn't seem like a lot—and it isn't—but if you think you're cutting it fine, don't give up. The second and third shards slow time down just enough to make this doable. I reached the Looker when I had literally 0.00 left on my timer.

So, good luck. It's a bit tricky, but this'll also unlock a badge to contribute to the Something Smells Rank achievement.

Update: I've now added a video guide of the achievement, courtesy of the great BOB101910 RFP.

So thanks to him.

My personal recommendation is to try this achievement on 1,000,000 BC - Level 3, but it is possible on ANY non-boss level including the first level of the game.

To get this achievement, you'll need to touch the "Looker" which looks similar to a shard that is somewhere near the end of every level. This will trigger a small timer that will show up in the top right of the screen near the glorbs/shards counter.

Once you touch it, you'll now have to rewind all the way back to the beginning of the level, and you'll have to get back to that location and touch it again while the time is in the positive. Easier said than done. On this level, you have 40.000 seconds to complete the entire level and get to the Looker again which will look like a Hero until it expires.

As for tips... first is practice and comprehension of the game. After that, get through the level as fast as possible, then rewind and respawn another guy to get through it faster and faster and faster every time. Eventually you'll have a collection of guys flying through the level like a huge wall of bullets. I ONLY used Jean Rambois' charged attack for the entire level, and that'll work for this level as well.

Chokepoints are the places that you need to take care of the fastest, as these slow you down the most. These includes doors, cliffs or mini-bosses that need to be destroyed before you are allowed to continue. It is important to have MAXIMUM firepower at these points in order to minimize lost time.

Also, Shards are VERY IMPORTANT. You'll want to "save" them whenever possible, and only start using them as your approaching final few runs. Also, in order to have as many versions of your character using shards at the same time, you'll want to give youself a small delay before shooting a shard, and then after rewinding, you can shoot it a little bit faster. This will let you have the slo-mo, but also have other characters in slo-mo with you. Ideally you want as many different versions of yourself in slo-mo as possible as this will give you the best chance.

The video will help explain these things even further:

While the two previous solutions have great info and good videos I found those strategies somewhat difficult for me. So I did some searchng on YouTube and stumbled across this beauty. This is done on the first level of the game and the gamer takes a simpler approach to it as oppose to the more chaotic walk troughs out there. It's really all about hitting the last two shards at the right moment and having just a few clones of yourself helping you clear the path. Perfectly timed jumps are also required. Got it on my first attempt after watching the video.

This video was made by ID@Upload and all credit goes to him/her

Hope this proves useful and good luck.